The present disclosure relates generally to the determination of frequency, location and time. More particularly, the present disclosure relates to determining frequency, location and time based on television signals, satellite positioning signals, signals of opportunity, and the like. This knowledge of frequency, location and time has many applications. For example, knowledge of frequency, location and time can be used to fulfill the requirements of consumer wireless mobile telephone base stations referred to as “femtocells.”
Wireless mobile telephones are gaining in popularity. However, many consumers have retained their conventional wired telephones, in part due to their superior reliability compared to wireless mobile telephones. In particular, wireless mobile telephone signals are often attenuated or blocked inside buildings, leading to dropped calls, reduced data rates, and the like.
To address these reliability problems, consumer wireless mobile telephone base stations, referred to as “femtocells,” are being introduced to the marketplace. FIG. 1 shows a prior art wireless mobile telephone system 100 that includes a femtocell 102. Referring to FIG. 1, wireless mobile telephone system 100 also includes a “macrocell” 104, which includes a conventional wireless mobile telephone antenna 106 and a conventional wireless mobile telephone base station 108, which is in turn connected to the public switched telephone network (PSTN) 110.
Femtocell 102 also includes a conventional wireless mobile telephone antenna 128. Femtocell 102 is generally connected to PSTN 110 by a broadband connection to the Internet 114. A wireless mobile telephone 116 can communicate with other telephones connected to PSTN 110 by exchanging wireless mobile telephone signals 118 with macrocell 104 and femtocell 102.
A key requirement for any sort of base station, whether it be a macrocell 104 or a femtocell 102, is precise knowledge of frequency and time. This knowledge is required to synchronize the bases stations, which otherwise would interfere with each other. In addition, precise knowledge of time is required for operations such as handovers from one base station to another. The precise determination of time in turn involves precise knowledge of location.
The information required for this precise determination of time and location is generally acquired from satellite positioning systems such as the Global Positioning System (GPS). Referring again to FIG. 1, GPS satellites 120 provide GPS signals 122 that can be used to obtain precise knowledge of time and location. Base stations generally include GPS antennas to obtain GPS signals 122. In system 100, macrocell 104 includes a GPS antenna 124, and femtocell 102 includes a GPS antenna 126.
Conventional femtocells rely upon GPS signals to obtain precise knowledge of time and location. However, GPS signals are often attenuated or blocked indoors, where femtocells are usually deployed. The required GPS signals can only be obtained by locating the femtocell near a window with a suitable view of the GPS satellites, connecting an expensive GPS antenna to the femtocell, and the like.